Biogas, biohydrogen, and polyhydroxyalkanoates production from organic waste in the circular economy context

Resumen

A circular economy is an economic system aimed at minimizing waste and making the most of resources. Anaerobic digestion (AD) is a technology of great interest for the circular economy approach since it combines the treatment of high organic load wastes with the production of energy vectors (EV): biogas and biohydrogen. In this chapter, a brief description of the AD process characteristics is presented, including the two main configurations that lead to the production of the aforementioned EV: the single-stage process for methane-rich biogas generation and the dark fermentation process to generate hydrogen-rich biogas, together with volatile fatty acids (VFAs). Moreover, an overview of the production yields of both EV from different organic wastes generated in urban areas and rural zones with agro-industrial activity is addressed. Likewise, the use of VFAs for the generation of high value-added products through biorefinery processes is also reported. Among these products, polyhydroxyalkanoates should be highlighted. This option promotes the production of biobased and biodegradable bioplastics from organic wastes as a sustainable route and an attractive alternative to petroleum-based plastics. It is, therefore, an option framed in the context of both the circular economy and the green economy.